The present invention relates to transformers, and more specifically, the invention relates to a laminated transformer system and method.
Transformers are electrical devices commonly used to transfer an alternating current or voltage from one electric circuit to another by means of electromagnetic induction. A transformer typically consists of two or more conductor windings placed on the same iron core magnetic path. The conductor windings, or coils, produce a magnetic field flux that is associated with the electrical current that passes through them. The iron core is generally made up of sheets or laminations of rolled iron, such as electrical grade steel. Laminating the core minimizes magnetic eddy current production and hysteresis. The iron may be treated so that it has a high magnetic conduction quality, or permeability, throughout the length of the core. One application of a transformer, for example, is as a ballast component in a high-intensity discharge lamp. In this and other applications, the transformer should function in a quiet and efficient manner while minimizing heat production.
Currently, transformer cores may be welded at two locations that serve to hold the laminations primarily in a horizontal direction. A shortcoming of this welding strategy is that the individual laminations may separate at their corners in a vertical direction. Repeated handling or lifting of the transformer produces stress forces on the unit that may result in a xe2x80x98fanningxe2x80x99 of the lamination corners. The separation of the lamination corners may be visually unappealing and may even result in increased noise production and failure of the transformer.
In order to prevent the xe2x80x98fanningxe2x80x99 of the laminations, additional welds have been applied near the corners of the transformer core. This strategy has been proven effective for preventing lamination separation, but has also resulted in disruption of the magnetic field flux. The additional material introduced by the weld and subsequent deformation of the transformer housing typically results in the formation of magnetic eddies and, as a consequence, hysteresis. This may reduce the efficiency of the unit and produce additional heat. As such, welding the laminations near the corners is not a practical solution for the prevention of xe2x80x98fanningxe2x80x99.
In summary, the laminations of transformer cores are typically held together by a set of primary welds. The primary welds, however, do not prevent the separation of the laminations at their corners. Previous attempts to bond the laminations near their corners have resulted in reduced unit efficiency and increased hysteresis and heat generation of the transformer. Therefore, it would be desirable to achieve a strategy for bonding the transformer laminations in a manner that overcomes the aforementioned and other disadvantages.
One aspect of the invention provides a transformer system. The transformer system includes a laminated housing with a plurality of laminates. A coil assembly producing a magnetic field is positioned within the laminated housing. At least one low power weld is positioned on the laminated housing to bond the laminates together without substantially disrupting the magnetic field. The low power weld may comprise a tungsten inert gas weld and may comprise a low penetration weld. The low power weld may be applied with a power setting of about 100 amps and may be positioned adjacent an outer edge of the laminated housing. At least one primary weld may be applied on the laminated housing to bond the laminates together. The primary weld may be applied with a power setting of about 170 amps. The laminates may comprise an electrical grade steel material and may comprise a magnetic core. The coil assembly may be disposed on the magnetic core.
Another aspect of the invention provides a method of attaching a laminated housing on a transformer. The method includes applying a low power weld to the laminated housing including a plurality of laminates. The laminates are bonded together without substantially disrupting a magnetic field produced by a coil assembly positioned within the laminated housing. The low power weld may comprise a tungsten inert gas weld and may comprise a low penetration weld. The low power weld may be applied with a power setting of about 100 amps and may be positioned adjacent an outer edge of the laminated housing. At least one primary weld may be applied on the laminated housing to bond the laminates together. The primary weld may be applied with a power setting of about 170 amps. The laminates may comprise an electrical grade steel material and may comprise a magnetic core. The coil assembly may be disposed on the magnetic core.
The foregoing and other features and advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention rather than limiting, the scope of the invention being defined by the appended claims and equivalents thereof.